Nozzle device for a turbocharger and associated control method

ABSTRACT

A variable nozzle device for a turbocharger comprises an annular arrangement of vanes disposed in a nozzle formed between an inner wall and an outer wall, said outer wall being constituted by an axially displaceable member, wherein said axially displaceable member is displaceable by an action exerted from the side of the inner wall.

The present invention relates to a variable nozzle device and inparticular to a variable nozzle device for a turbocharger. Also, theinvention relates to a method for controlling a variable nozzle device,in particular of a turbocharger.

In a conventional turbocharger apparatus for use in association withinternal combustion engines a variable nozzle vane assembly is knownfrom the state of the art. The conventional turbocharger apparatuscomprises an exhaust gas driven turbine and an inlet air compressor. Theinlet air compressor is driven by power generated by the exhaust gasdriven turbine wherein a turbine wheel of the exhaust gas driven turbineis mounted on a common shaft with a compressor impeller of the inlet aircompressor.

The conventional turbocharger apparatus is provided with a housinghaving an exhaust gas inlet for supplying the exhaust gas to the exhaustgas turbine. In a passage for supplying the exhaust gas to the exhaustgas turbine, vanes are provided to force the flow of the exhaust gasinto a predetermined direction.

According to the state of the art, the vanes are variable, e.g. by theprovision of pivotable vanes such that a geometric arrangement of theflow passage is adjustable according to the conditions of the flow ofthe exhaust gas.

It is the object of the present invention to provide a variable nozzledevice for a turbocharger with an improved configuration and an enhancedefficiency and to provide a control method for a variable nozzle device,in particular for a turbocharger.

The object is solved by a variable nozzle device having the features ofclaim 1, by a variable nozzle device having the features of claim 11,and/or by a method having the features of claim 19.

Further developments of the invention are set forth in the dependentclaims.

According to an aspect of the invention, a variable nozzle device for aturbocharger comprises an annular arrangement of vanes between an innerwall and an outer wall, wherein said outer wall is constituted by anaxially displaceable member. Furthermore, said axially displaceablemember is displaceable by an action exerted from the side of the innerwall. This means that the movement of said displaceable member, forexample such as a hollow piston member, can be effected from the side ofthe inner housing which accommodates actuating elements of theturbocharger.

With this arrangement, the entire structure can be simplified and thereliability thereof can be improved, since the actuating from the sideof the inner housing can be assembled more easily and a furtheractuating mechanism at the side of the outer housing of the turbochargercan be omitted.

Furthermore, by means of a structure according to the invention, furtheroptions of actuating the axially displaceable member are enabled.

Preferably, said action is exerted by an engagement of said axiallydisplaceable member with an actuating member on the side of said innerwall. The engagement of said inner side wall effects the displacement ofthe axially displaceable member such that any movement of said movablemember on the side of the inner wall can be applied as long as anengagement is provided. It is preferable that said axially displaceablemember is displaceable by a movement of said movable member on saidinner wall along an inclined portion of said axially displaceablemember. Between said inner wall and said outer wall an annular inflowpassageway for supplying an exhaust gas to an exhaust gas turbine isformed. The cross-sectional area of said inflow passageway is increasedby displacing said axially displaceable member away from said innerwall. Preferably, said annular arrangement of vanes is provided on saidinner wall.

By means of this arrangement, the cross-sectional area of the passagewaycan be adjusted corresponding to e.g. the operational condition of theengine. The inclined portion can be adjusted or tuned so as to providethe nozzle device with a predetermined behavior.

Preferably, said vanes each comprise at least two portions which aremovable relative to each other. Preferably, said vanes are directed in adirection so as to direct the flow of the fluid substantially in atangential direction with respect to the annular arrangement. Thereby itis possible to change not only the effective size of the vane but alsothe geometrical relations of the entire nozzle device. It is preferablethat said two portions which are movable relative to each other compriseat least one fixed vane member and one movable vane member. Furthermore,said movable vane member is movable relative to said fixed vane memberin the radial direction so as to change the radial length of said vane.Thereby, the nozzle opening amount or degree can be adjusted withrespect to the cross-sectional area of an inflow passageway and also thegeometry is adjustable. Preferably, the movable vane member constitutessaid actuating member.

Preferably, said fixed vane member and said movable vane member protrudefrom a fixed vane plate and a movable vane plate. Furthermore, saidmovable vane plate is movable, preferably rotatable, with respect to thefixed vane plate, and said movable member on said inner wall side is atleast one of said movable vane members. This structure provides a simpleand reliable system due to a low number of moving components.

It is preferably that said axially displaceable member is displaced bysaid movement of said movable vane member when said movable vane memberis in a predetermined position range. Also preferably, by moving saidmovable vane member said annular inflow passageway is gradually openedor closed. Furthermore, said axially displaceable member is moved toopen said annular inflow passageway as said movable vane member is movedto open said annular inflow passageway.

By means of this arrangement, both the displacement of said axiallydisplaceable member and the actuation of said vanes is enabled by asingle actuation mechanism. By a predetermined design of the engagementportion, the relation of the adjustment of the axially displaceablemember and the adjustment of the vanes can be freely selected.

According to a further aspect of the invention, a variable nozzle devicefor a turbocharger is provided, which comprises an annular arrangementof vanes, wherein each vane comprises at least two portions movablerelatively to each other in a circumferential direction. Preferably, oneof said at least two portions forms an adjustable extension of said vanein the circumferential direction of said annular arrangement. Alsopreferably, said two portions comprise a fixed vane member and a movablevane member.

With this structure, a simple nozzle device is provided which comprisesa low number of moving components thereby increasing the reliability. Itis preferable that said fixed vane member and said movable vane memberprotrude from a fixed vane plate and a movable vane plate, respectively,and form a nozzle ring. Said movable vane plate is preferably rotatablerelative to said fixed vane plate. Only two movable members enable theadjusting of the vane assembly by rotating one vane plate relative tothe other. Thereby, the structure can be made simple and reliable.

Preferably, by rotating said movable vane plate relative to said fixedvane plate, a circumferential length of said vane is adjustable. Also,by rotating said movable vane plate relative to said fixed vane plate,an opening amount of said nozzle device is gradually adjustable.

According to the invention, said movable vane plate is rotatable by anactuator mechanism. Preferably, the movement of said vane members isrestricted by a restriction means. Also, said movable vane member isurged towards a closing direction of said nozzle device relative to saidfixed vane member by a spring member. The restricting means and/or thespring member enhances the function and reliability of the nozzledevice. Further, a closed position is ensured in the case of failure ofthe actuating system, and the maximum opening amount can be set inaccordance with mechanical and/or structural values.

According to a further aspect of the invention, a method for controllinga variable nozzle device of a turbocharger is provided which comprises aplurality of vanes arranged in a nozzle defined between an inner walland an outer wall, said vanes forming nozzle passages, said methodcomprising the steps of:

-   -   adjusting the nozzle passages by adjusting said vanes, and    -   adjusting the nozzle by varying the interval between said inner        wall and said outer wall,    -   wherein the adjusting of said nozzle is achieved in response to        said adjusting of the nozzle passages and vice versa.

Preferably, said interval between said inner wall and said outer wall isgradually increased as said nozzle passages open. Also preferably, saidinterval between said inner wall and said outer wall is varied by saidadjusting of said nozzle passages when said nozzle passages are in apredetermined opening range.

The adjusting of said nozzle is preferably achieved by a singleactuating mechanism.

In the method, said axially displaceable member forming said outer wallis gradually moved axially towards an opening direction as said movablevane member is moved towards a direction of opening said annular inflowpassageway.

By means of the method according to the invention, the degrees offreedom of the axially displaceable member and of the vanes can be usedto adjust the cross-sectional inflow area of the annular passageway.Also, the cooperation of the axially displaceable member with the vanescan sufficiently be set. Therefore, it is possible to design thearrangement such that the opening amount of the vane assembly relativeto the opening amount of said axially displaceable member is set to anoptimum relation depending on the requirements of the entire system.

It is to be noted that the features set forth above and as defined inthe claims can be freely combined. That is, the invention can beembodied only having the axially displaceable member or only theadjustable vanes. In the case that both the axially displaceable memberand the adjustable vanes are applied, it is possible that they areoperated independently or by cooperating with each other.

Preferred embodiments of the invention are explained by way of exampleswith reference to the accompanying drawings.

FIG. 1 shows an embodiment of the variable nozzle device according tothe invention in a closed position.

FIG. 2 shows the variable nozzle device of FIG. 1 in a mid-openposition.

FIG. 3 shows the variable nozzle device of FIG. 1 in a fully openposition.

FIG. 4A shows a portion of the variable nozzle device with an actuatoraccording to an embodiment of the invention in a closed position.

FIG. 4B is a bottom view of FIG. 4A

FIG. 5 shows a portion of the variable nozzle device of FIG. 4A in amid-open position.

FIG. 6A shows a portion of the variable nozzle device of FIG. 4A in afully open position.

FIG. 6B is a bottom view of FIG. 6A.

FIG. 7 shows a turbocharger apparatus according to an embodiment of thepresent invention having the variable nozzle device in a partiallycut-away view wherein the turbine wheel is omitted.

FIG. 8A shows the turbocharger apparatus according to an embodiment ofthe present invention in a cross-sectional view in a closed position.

FIG. 8B and FIG. 8C show the nozzle ring used in the turbochargerapparatus of FIG. 8A in the fully closed position.

FIG. 9A shows the turbocharger apparatus according to an embodiment ofthe present invention in a cross-sectional view in a mid open position.

FIG. 9B and FIG. 9C show the nozzle ring used in the turbochargerapparatus of FIG. 9A in the mid open position.

FIG. 10A shows the turbocharger apparatus according to an embodiment ofthe present invention in a cross-sectional view in a fully openposition.

FIG. 10B and FIG. 10C show the nozzle ring used in the turbochargerapparatus of FIG. 10A in the closed position.

FIG. 11A shows a portion of the nozzle ring in a closed position.

FIG. 11B shows a portion of the nozzle ring in an open position.

An embodiment of the present invention is explained with reference tothe Figures.

First, a turbocharger apparatus according to an embodiment of thepresent invention is explained with reference to FIG. 7 and FIG. 8A.According to FIG. 7, the turbocharger apparatus is provided with ahousing which comprises an exhaust gas turbine housing 1 and an inletair compressor housing 2.

According to FIG. 8A, in the inlet air compressor housing 2, an inletair compressor is accommodated which comprises an inlet air compressorimpeller 20. The inlet air compressor impeller 20 is mounted on a shaft24 which is rotatably supported in the housing.

In the exhaust gas turbine housing 1, an exhaust gas turbine isaccommodated, which comprises an exhaust gas turbine wheel 22 which ismounted on the same shaft 24 as the inlet air compressor impeller 20.The exhaust gas turbine housing 2 is arranged so as to surround theexhaust gas turbine wheel 22. In particular, a flow passage 13 whichforms a volute is formed around the wheel 22. On a tangential portion ofthe housing, an exhaust gas inlet 17 is provided, as shown in FIG. 7.

As shown in FIG. 7 and 8A, in the exhaust gas turbine housing 1, avariable vane means and a sliding piston device (axially displaceablemember) 5 are provided so as to substantially surround the exhaust gasturbine wheel 22. The sliding piston device 5 forms the exhaust gasoutlet of the turbocharger apparatus. The sliding piston device consistsof a tubular member which is slidably supported in an outlet portion ofthe exhaust gas turbine housing 1 so as to be movable in the axialdirection of the shaft. According to the embodiment, the sliding pistonmember forms an outer wall of the exhaust gas inlet.

The variable vane means 4 a, 4 b, 6, 7 and the sliding piston device 5are further explained with reference to the Figures. FIG. 1 is adetailed illustration of the variable vane means and the sliding pistondevice according to the present embodiment of the invention.

The variable vane means comprises a nozzle ring surrounding the exhaustgas turbine wheel 22. The nozzle ring according to the embodiment formsa dividable device which constitutes an inner wall of the exhaust gasturbine. The variable vane means includes said nozzle ring having vanes4 a, 4 b and vane support plates 6, 7.

The variable vane means comprises a fixed vane support plate 6 and amovable vane support plate 7. The fixed vane support plate 6 issubstantially circular in shape and is provided with an opening in acenter portion thereof. In said opening of the fixed vane support 6plate, the movable vane support plate 7 is inserted. The outer diameterof the movable vane support plate 7 is set so as to enable a slidingrotation thereof with respect to the fixed vane support plate 6.According to the embodiment, the fixed support plate 6 and/or themovable support plate forms the inner wall of the exhaust gas inlet.However, it is also possible that the fixed vane support is formed as aninner plate wherein the movable vane support is formed radially outwardof the fixed vane support. Also, both vane supports can be formedrotatably relative to each other.

As shown in FIGS. 8A and 8B, a plurality of fixed vanes 4 a is arrangedon one surface of the fixed vane support plate 6 so as to protrudetherefrom. The vanes are substantially fan-shaped and slightly obliquewith respect to the tangent of the fixed vane support plate 6.

A plurality of movable vanes 4 b is arranged on one surface of themovable vane support plate 7 so as to protrude therefrom in the samedirection as the fixed vanes 4 a. The movable vanes 4 b are arrangedinward with respect to the fixed vanes 4 a, and the number of fixedvanes 4 a corresponds to the number of the movable vanes 4 b. The numberof fixed vanes 4 a and the number of the movable vanes 4 b are five inthe present embodiment but not limited to said number. The movable vanes4 b and the fixed vanes 4 a form two portions of a vane which aremovable relative to each other.

By rotating the movable vane support plate 7 relative to the fixed vanesupport plate 6, the movable vanes 4 b are moved relative to the fixedvanes 4 a. Therefore, the movable vanes 4 b are arranged in theprojection of the fixed vanes 4 a or form an extension of the fixedvanes 4 a in their direction of length in the tangential direction.

The function of the variable vane means according to the presentembodiment is described with reference to the Figures. In FIG. 4A andFIG. 4B, the variable vane means is shown in a closed position. That is,the movable vane support plate 7 is positioned with respect to the fixedvane support plate 6 such that the movable vanes 4 b extend from one endof the fixed vanes 4 a in the circumferential direction of the vanesupport plates. In FIG. 8A and FIG. 8B, the nozzle ring is shown in amore detailed view in a closed position.

A spring member 19 is provided between the movable vane support plate 7and the fixed vane support plate 6 so as to urge the movable vanesupport plate 7 towards an end position of the rotation of the movablevane support plate 7 with respect to the fixed vane support plate 6.Preferably, said end position of the movable vane support plate 7effects the closed position of the variable vane means, as shown in FIG.4B. However, as the end position of the movable vane support plate 7,each position such as the open position of the vane assembly can be setaccording to the system requirements.

On the side opposite to the side where the vanes are provided, anengagement device 21 is provided on the movable vane support plate 7, asshown in FIGS. 1-3. The engagement device 21 is capable of engaging witha portion of an actuating mechanism 10. By operating the actuatingmechanism 10, the movable vane support plate 7 is rotated relative tothe fixed vane support plate 6 against the force of the spring member19. Thereby, the movable vanes 4 b are moved in the rotational directionsuch that their side surfaces facing outward in the radial direction aremoved to gradually increase the area which is covered by side surfacesof the fixed vanes 4 a which face in an inward direction in the radialdirection.

By operating the actuating mechanism against the spring member 19, thevariable vane means is gradually opened and a mid-open position thereofis provided as shown in FIG. 5. That is, the space for supplying theexhaust gas to the turbine between each of the vanes is increased. FIG.9A shows the turbocharger apparatus according to the embodiment in themid-open position of the variable vane means. As shown in FIG. 9B andFIG. 9C, the nozzle ring is in a fully open position, while the slidingpiston member is held in the closed position.

The sliding piston device 5 is pressed toward the nozzle ring by a forceF, as shown e.g. in FIG. 9A, to maintain a sufficient pressure againstthe nozzle ring to provide an appropriate engagement between the slidingpiston device 5 and the nozzle ring.

By further operating the actuating mechanism 10 against the force of thespring member 19, the movable vane support plate 7 is further moved inthe rotational direction with respect to the fixed vane support plate 6.Thereby, a fully open condition of the variable vane means is achievedas shown in FIG. 6A and FIG. 6B. In FIG. 6B, a protrusion 23 abutsagainst the step 25 so as to limit the rotational movement of themovable vane support plate 7. FIG. 10A shows a more detailed view of theturbocharger apparatus according to the embodiment in the fully opencondition of the variable nozzle device. In this condition, the slidingpiston device and, as shown in FIG. 10B and FIG. 10C, the nozzle ringare fully open.

FIG. 11A and FIG. 11B are partial views of the nozzle ring according tothe embodiment of the present invention. The nozzle ring in FIG. 11A isin the fully closed position, thereby generating a passage 3 between thefixed vanes 4 a and the movable vanes 4 b. The nozzle ring shown in FIG.11B is in the fully open position, and the passage 3 between the fixedvanes 4 a and the movable vanes 4 b is accordingly widened in comparisonwith the passage 3 shown in FIG. 11A.

The cooperation between the variable vane means and the sliding pistondevice is explained with reference to FIG. 1-FIG. 3. As shown in FIG. 1,the sliding piston device is provided adjacent in the axial direction ofthe piston 5 such that the piston 5 slidably abuts against its axial endface with the axial end faces of the movable vanes 4 b. A protrusion 11is provided at said abutting face of the piston 5 which is provided withan inclined portion 12. The inclined portion 12 is capable to be broughtinto engagement with an end face of the movable vane 4 b by rotating themovable vane support plate 7 to the opening direction of the variablevane means.

The piston 5 is slidably supported in the exhaust gas turbine housing 2so as to be movable in the axial direction with respect to the variablevane means.

When the actuating mechanism 10 is operated starting from the fullyclosed position of the variable vane means, the movable vane 4 b ismoved slidably along the end face of the piston. Thereby, the variablevane means is gradually opened and the piston substantially keeps itsaxial position.

When the actuating mechanism 10 is further operated against the force ofthe spring member 19, the inclined portion 12 of the protrusion 11 comesinto engagement with the end face of the movable vane 4 b. Thiscondition is shown in FIG. 2. That is, the variable vane means is in amid-open position.

When the actuating mechanism is further operated, the end face of themovable vane 4 b presses the inclined portion 12 of the protrusion 11and thereby gradually moves the piston 5 axially away from the variablevane means as the actuating mechanism 10 is further operated.

Thereby, the space for passing through the exhaust gas into the turbineis further increased.

According to the present invention, only one single actuating mechanismis required to operate two different members for adjusting thecharacteristics of the exhaust gas flow passage of the turbochargerapparatus.

In the present invention, the movable vanes 4 b are formed so as toprotrude beyond the fixed vanes 4 a. Therefore, the geometriccharacteristic of the exhaust gas inlet can be further improved in thecondition that the piston is axially moved away from the variable vanemeans. That is, there is no gap in the flow passage which is notprovided with a vane even if the piston is moved as far away as possiblefrom the variable vane means. Thereby, the undirected flow of theexhaust gas can be avoided irrespective of the adjusting condition ofthe variable vane means or the sliding piston member. That is, theaxially displaceable member 5 is continuously in contact with at least aportion of the vane assembly. In the shown embodiment, the contactportion is formed as the protrusion 11.

Although the invention is explained in detail with reference to theparticular embodiment, the invention is not limited to the structures ofthe embodiment. In particular, the fixed vanes and/or the movable vanescan both be movable and displaceable relative to each other.Furthermore, the invention is not limited to the structure applying themovable vane plate and the fixed vane plate. Any structure can beapplied which enables portions of the vanes to be movable relative toeach other. The engagement of the axially displaceable member with theportion of the vanes is not limited to the protrusion and/or theinclined surface portion. Any engagement can be applied as long as thevanes cooperate with the axially displaceable member. Finally, it is tobe noted that the variable vane means and the axially displaceablemember can be applied separately or in combination with each other.

1. A variable nozzle device for a turbocharger comprising an annulararrangement of vanes (4) disposed in a nozzle formed between an innerwall (6, 7) and an outer wall, said outer wall being constituted by anaxially displaceable member (5), wherein said axially displaceablemember (5) is displaceable by an action exerted from the side of saidinner wall.
 2. A variable nozzle device according to claim 1, whereinsaid action is exerted by an engagement of said axially displaceablemember (5) with an actuator member (4 b) on said inner wall.
 3. Avariable nozzle device according to claim 2, wherein said axiallydisplaceable member (5) is displaceable by a rotational movement of saidactuator member (4 b).
 4. A variable nozzle device according to claim 3,wherein said annular arrangement of vanes (4) is provided on said innerwall (6, 7).
 5. A variable nozzle device according to claim 4, whereinsaid vanes (4) each comprise at least two portions (4 a, 4 b) which aremovable relative to each other.
 6. A variable nozzle device according toclaim 5, wherein said two portions (4 a, 4 b) which are movable relativeto each other comprise at least one fixed vane member (4 a) and onemovable vane member (4 b).
 7. A variable nozzle device according toclaim 6, wherein said movable vane member (4 b) constitutes saidactuator member.
 8. A variable nozzle device according to claim 6 or 7,wherein said fixed vane member (4 a) and said movable vane member (4 b)protrude from a fixed vane plate (6) and a movable vane plate (7)rotatable relative to each other and forming a nozzle ring.
 9. Avariable nozzle device according to claim 8, wherein said axiallydisplaceable member (5) is displaced by said movement of said movablevane member (4 b) when said movable vane member (4 b) is in apredetermined position range.
 10. A variable nozzle device according toclaim 9, wherein said axially displaceable member (5) is moved by saidmovable vane member to open said annular inflow passageway (3) as saidmovable vane members (4 b) are moved to open nozzle passages (3) formedbetween said vanes.
 11. A variable nozzle device for a turbocharger,comprising an annular arrangement of vanes (4), each vane comprising atleast two portions (4 a, 4 b) movable relative to each other in acircumferential direction.
 12. A variable nozzle device according toclaim 11, wherein one of said at least two portions forms an adjustableextension of said vane in the circumferential direction of said annulararrangement.
 13. A variable nozzle device according to claim 12, whereinsaid two portions comprise a fixed vane member (4 a) and a movable vanemember (4 b).
 14. A variable nozzle device according to claim 13,wherein said fixed vane member (4 a) and said movable vane member (4 b)protrude from a fixed vane plate (6) and a movable vane plate (7),respectively, said plates being rotatable relative to each other.
 15. Avariable nozzle device according to claim 14, wherein an opening amountof said nozzle device is gradually adjustable by rotating said movablevane plate (7) relative to said fixed vane plate (6).
 16. A variablenozzle device according to claim 14 or 15, wherein said movable vaneplate (7) is rotatable by an actuator mechanism (10).
 17. A variablenozzle device according to one of claims 13-16, wherein said movement ofsaid vane members (4 a, 4 b) is restricted by a restriction means (23,25).
 18. A variable nozzle device according to one of claims 13-17,wherein said movable vane member (4 b) is urged toward a closingdirection of said nozzle device relative to said fixed vane member (4 a)by a spring member (19).
 19. A method for controlling a variable nozzledevice of a turbocharger comprising a plurality of vanes arranged in anozzle defined between an inner wall and an outer wall, said vanesforming nozzle passages (3), said method comprising the steps of:adjusting the nozzle passages by adjusting said vanes, and adjusting thenozzle by varying the interval between said inner wall and said outerwall, wherein the adjusting of said nozzle is achieved in response tothe adjusting of said nozzle passages (3), and vice versa.
 20. A methodaccording to claim 19, wherein said interval between said inner wall andsaid outer wall is gradually increased as said nozzle passages open. 21.A method according to claim 20 or 21, wherein said interval between saidinner wall and said outer wall is varied by the adjusting of said nozzlepassages when said nozzle passages are in a predetermined opening range.22. A method according to one of claims 19-21, wherein the adjusting ofsaid nozzle is achieved by a single actuating mechanism.